Alpha-olefins may be manufactured in high yield and with very high selectivity by contacting ethylene with an iron complex of a selected 2,6-pyridinedicarboxaldehyde bisimine or a selected 2,6-diacylpyridine bisimine, and usually a selected activator compound.
Alpha-olefins, especially those containing about 6 to about 20 carbon atoms, are important items of commerce, with about 1.5 million tons reportedly being produced in 1992. The xcex1-olefins are used as intermediates in the manufacture of detergents, as monomers (especially in linear low density polyethylene), and as intermediates for many other types of products. As a consequence, improved methods of making these compounds are of interest.
Most commercially produced xcex1-olefins are made by the oligomerization of ethylene, catalyzed by various types of compounds, see for instance B. Elvers, et al., Ed. Ullmann""s Encyclopedia of Industrial Chemistry, Vol. A13, VCH Verlagsgesellschaft mbH, Weinheim, 1989, p. 243-247 and 275-276, and B. Cornils, et al., Ed., Applied Homogeneous Catalysis with Organometallic Compounds, A Comprehensive Handbook, Vol. 1, VCH Verlagsgesellschaft mbH, Weinheim, 1996, p. 245-258. The major types of commercially used catalysts are alkylaluminum compounds, certain nickel-phosphine complexes, and a titanium halide with a Lewis acid such as AlCl3. In all of these processes significant amounts of branched and/or internal olefins and/or diolefins, are produced. Since in most instances these are undesired, and often difficult to separate from the desired linear xcex1-olefins, minimization of these byproducts is sought.
This invention concerns a first process for the production of xcex1-olefins, comprising, contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +300xc2x0 C., a compound of the formula 
with ethylene and:
(a) a first compound W, which is a neutral Lewis acid capable of abstracting Xxe2x88x92 an alkyl group or a hydride group from Fe to form WXxe2x88x92, (WR20)xe2x88x92 or WHxe2x88x92 and which is also capable of transferring an alkyl group or a hydride to Fe, provided that WXxe2x88x92 is a weakly coordinating anion; or
(b) a combination of second compound which is capable of transferring an alkyl or hydride group to Fe and a third compound which is a neutral Lewis acid which is capable of abstracting Xxe2x88x92, a hydride or an alkyl group from Fe to form a weakly coordinating anion;
wherein:
each X is an anion;
n is 1, 2 or 3 so that the total number of negative charges on said anion or anions is equal to the oxidation state of an Fe atom present in (I);
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R9, R10, R11, R14, R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group; and
R20 is alkyl;
and provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group or a secondary carbon group and the remainder of R12, R13, and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R14 are hydrogen; and
any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.
Also disclosed herein is a compound of the formula 
wherein:
each X is an anion;
n is 1, 2 or 3 so that the total number of negative charges on said anion or anions is equal to the oxidation sate of a Fe atom present in (I);
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; and
R9, R10, R11, R14, R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
and provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group or a secondary carbon group and the remainder of R12, R13 , and R17 are hydrogen; and
when R8 is a tertiary carbon group all of R12, R13 and R14 are hydrogen; any two of R8, R9, R10, R11, R12 , R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.
This invention includes a compound of the formula 
wherein:
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; and
R9, R10, R11, R14, R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl; R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
and provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group or a secondary carbon group and the remainder of R12, R13 , and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R14 are hydrogen; and
any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.
This invention also concerns a second process for the production of xcex1-olefins, comprising contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +300xc2x0 C., a Fe[II] or Fe[III] complex of a tridentate ligand of the formula 
with ethylene, wherein:
R, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R9, R10, R11, R14, R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
and provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group or a secondary carbon group and the remainder of R12, R13, and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R14 are hydrogen;
any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring;
an Fe[II] or Fe[III] atom also has bonded to it an empty coordination site or a ligand that may be displaced by said ethylene, and a ligand that may add to said ethylene.
This invention also includes a compound of the formula 
wherein:
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl,
R9, R10, R11, R14,R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
T1 is hydride or alkyl or any other anionic ligand into which ethylene can insert;
Y is a vacant coordination site, or neutral ligand capable of being displaced by ethylene;
Q is a relatively non-coordinating anion; and
P is a divalent (poly)ethylene group of the formula xe2x80x94(CH2CH2)xxe2x80x94 wherein x is an integer of 1 or more;
and provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group or a secondary carbon group and the remainder of R12, R13, and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R14 are hydrogen; and
any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.
This invention also concerns a third process for the production of xcex1-olefins, comprising, contacting, at a temperature of about xe2x88x92100xc2x0 C. to about +300xc2x0 C., ethylene and a compound of the formula 
wherein:
R1, R2 and R3 are each independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an inert functional group;
R4 and R5 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl,
R9, R10, R11, R14, R15 and R16 are each independently hydrogen, hydrocarbyl, an inert functional group or substituted hydrocarbyl;
R8 is a primary carbon group, a secondary carbon group or a tertiary carbon group;
T1 is hydride or alkyl or any other anionic ligand into which ethylene can insert;
Y is a vacant coordination site, or a neutral ligand capable of being displaced by ethylene;
Q is a relatively non-coordinating anion; and
P is a divalent (poly)ethylene group of the formula xe2x80x94(CH2CH2)xxe2x80x94 wherein x is an integer of 1 or more;
and provided that:
when R8 is a primary carbon group none, one or two of R12, R13 and R17 are primary carbon groups, and the remainder of R12, R13 and R17 are hydrogen;
when R8 is a secondary carbon group, none or one of R12, R13 and R17 is a primary carbon group or a secondary carbon group and the remainder of R12, R13, and R17 are hydrogen;
when R8 is a tertiary carbon group all of R12, R13 and R14 are hydrogen; and
any two of R8, R9, R10, R11, R12, R13, R14, R15, R16 and R17 vicinal to one another, taken together may form a ring.
Herein, certain terms are used. Some of them are:
A xe2x80x9chydrocarbyl groupxe2x80x9d is a univalent group containing only carbon and hydrogen. If not otherwise stated, it is preferred that hydrocarbyl groups herein contain 1 to about 30 carbon atoms.
By xe2x80x9csubstituted hydrocarbylxe2x80x9d herein is meant a hydrocarbyl group which contains one or more substituent groups which are inert under the process conditions to which the compound containing these groups is subjected. The substituent groups also do not substantially interfere with the process. If not otherwise stated, it is preferred that substituted hydrocarbyl groups herein contain 1 to about 30 carbon atoms. Included in the meaning of xe2x80x9csubstitutedxe2x80x9d are heteroaromatic rings.
By xe2x80x9c(inert) functional groupxe2x80x9d herein is meant a group other than hydrocarbyl or substituted hydrocarbyl which is inert under the process conditions to which the compound containing the group is subjected. The functional groups also do not substantially interfere with any process described herein that the compound in which they are present may take part in. Examples of functional groups include halo (fluoro, chloro, bromo and iodo), ether such asxe2x80x94OR18 wherein R18 is hydrocarbyl or substituted hydrocarbyl. In cases in which the functional group may be near an iron atom, such as R4, R5, R8, R12, R13, and R17 the functional group should not coordinate to the iron atom more strongly than the groups in compounds containing R4, R5, R8, R12, R13, and R17 which are shown as coordinating to the iron atom, that is they should not displace the desired coordinating group.
By an xe2x80x9calkyl aluminum compoundxe2x80x9d is meant a compound in which at least one alkyl group is bound to an aluminum atom. Other groups such as alkoxide, oxygen, and halogen may also be bound to aluminum atoms in the compound. See below for preferred alkylaluminum compounds.
By xe2x80x9cneutral Lewis basexe2x80x9d is meant a compound, which is not an ion, which can act as a Lewis base. Examples of such compounds include ethers, amines, sulfides, and organic nitriles.
By xe2x80x9ccationic Lewis acidxe2x80x9d is meant a cation which can act as a Lewis acid. Examples of such cations are sodium and silver cations.
By relatively noncoordinating (or weakly coordinating) anions are meant those anions as are generally referred to in the art in this manner, and the coordinating ability of such anions is known and has been discussed in the literature, see for instance W. Beck., et al., Chem. Rev., vol. 88 p. 1405-1421 (1988), and S. H. Strauss, Chem. Rev., vol. 93, p. 927-942 (1993), both of which are hereby included by reference. Among such anions are those formed from alkylaluminum compounds, defined above, and Xxe2x88x92, including R93AlXxe2x88x92, R92AlClXxe2x88x92, R9AlCl2Xxe2x88x92, and xe2x80x9cR9AlOXxe2x88x92xe2x80x9d. Other useful noncoordinating anions include BAFxe2x88x92 {BAF=tetrakis[3,5-bis(trifluoromethyl)phenyl]borate}, SbF6xe2x88x92, PF6xe2x88x92, and BF4xe2x88x92, trifluoromethanesulfonate, p-toluenesulfonate, (RfSO2)2Nxe2x88x92 (wherein Rf is perfluoroalkyl), and (C6F5)4Bxe2x88x92.
By formation of an xcex1-olefin is meant formation of a compound (or mixture of compounds) of the formula H(CH2CH2)qCH=CH2 wherein q is an integer of 1 to about 18. In most such reactions, a mixture of compounds will result which have differing values of q, and in most reactions to form the xcex1-olefins some of the xcex1-olefins formed will have q values of more than 18. Preferably less than 50 weight percent, more preferably less than 20 weight percent of the product mixture will have q values over 18. The product mixture may contain small amounts (preferably less than 30 weight percent, more preferably less than 10 weight percent, and especially preferably less than 2 weight percent) of other types of compounds such as alkanes, branched alkenes, dienes, and/or internal olefins.
By an empty coordination site is meant a potential coordination site that does not have a ligand bound to it. Thus if an ethylene molecule is in the proximity of the empty coordination site, the ethylene molecule may coordinate to the metal atom.
By a xe2x80x9cprimary carbon groupxe2x80x9d herein is meant a group of the formula xe2x80x94CH2---, wherein the free valence --- is to any other atom (the bond represented by the hyphen is to the benzene ring to which the primary carbon group is attached). Thus the free valence --- may be bonded to a hydrogen atom, halogen atom, a carbon atom, an oxygen atom, a sulfur atom, etc. In other words, the free valence --- may be to hydrogen, hydrocarbyl, substituted hydrocarbyl or a functional group. Examples of primary carbon groups include xe2x80x94CH3, xe2x80x94CH2CH(CH3)2, xe2x80x94CH2Cl, xe2x80x94CH2C6H5, xe2x80x94OCH3 and xe2x80x94CH2OCH3.
By a secondary carbon group is meant the group 
wherein both free bonds represented by the dashed lines are to an atom or atoms other than hydrogen. These atoms or groups may be the same or different. In other words the free valences represented by the dashed lines may be hydrocarbyl, substituted hydrocarbyl or functional groups. Examples of secondary carbon groups include xe2x80x94CH(CH3)2, xe2x80x94CHCl2, xe2x80x94CH(C6H5)2, cyclohexyl, xe2x80x94CH(CH3)OCH3, and xe2x80x94CHxe2x95x90CCH3.
By a xe2x80x9ctertiary carbon groupxe2x80x9d is meant a group of the formula 
wherein the solid line is the bond to the benzene ring and the three free bonds represented by the dashed lines are to an atom or atoms other than hydrogen. In other words, the bonds represented by the dashed lines are to hydrocarbyl, substituted hydrocarbyl or inert functional groups. Examples of tetiary carbon groups include xe2x80x94C(CH3)3, xe2x80x94C(C6H5)3, xe2x80x94CCl3, xe2x80x94C(CH3)2OCH3, xe2x80x94Cxe2x89xa1CH, xe2x80x94C(CH3)CHxe2x95x90CH2, and 1-adamantyl.
By a ligand that may add to ethylene is meant a ligand coordinated to a metal atom into which an ethylene molecule (or a coordinated ethylene molecule) may insert to start or continue an oligomerization. For instance, this may take the form of the reaction (wherein L is a ligand): 
Note the similarity of the structure on the left-hand side of this equation to compounds (V) and (VI) (see below).
Compounds useful as ligands are diimines of 2,6-pyridinedicarboxaldehyde or 2,6-diacylpyridines of the general formula 
wherein all of the xe2x80x9cRxe2x80x9d groups are as defined above. In preferred compounds (I) and (II), and all other preferred compounds in which the following xe2x80x9cRxe2x80x9d groups appear:
R4 and R5 are methyl or hydrogen; and/or
R1, R2, and R3 are all hydrogen; and/or
R9, R10, R11, R14, R15 and R16 are all hydrogen; and/or
R12 and R17 are each independently methyl, ethyl, propyl or isopropyl, more preferably both are methyl or ethyl; and/or
each X is a monovalent anion, more preferably selected from the group consisting of halide and nitrile.
It is also preferred that in all compounds in which they appear:
if R8 is a primary carbon group, R13 is a primary carbon group and R12 and R17 are hydrogen;
if R8 is a secondary carbon group, R13 is a primary or secondary carbon group, more preferably a secondary carbon group, and R12 and R17 are hydrogen.
In all specific preferred compounds in which they appear it is preferred that:
R4 and R5 are methyl, R9, R10, R11, R14, R15 and R16 are all hydrogen, and R12 and R17 are both methyl;
R4 and R5 are methyl, R9, R10, R11, R14, R15 and R16 are all hydrogen, and R12 and R17 are both ethyl;
R4 and R5 are methyl, R9, R10, R11, R14, R15 and R16 are all hydrogen, and R12 and R17 are both isopropyl;
R4 and R5 are methyl, R9, R10, R11, R14, R15 and R16 are all hydrogen, and R12 and R17 are both n-propyl;
R4 and R5 are methyl, R9, R10, R11, R14, R15 and R16 are all hydrogen, and R12 and R17 are both chloro; and
R4 and R5 are methyl, R9, R10, R11, R14, R15 and R16 are all hydrogen, and R12 and R17 are both trifluoromethyl.
In all of the above specific compounds it is preferred that X is selected from the group consisting of chloride, bromide and nitrate, and more preferably that it is chloride.
Compounds such as (II) and may be made by the reaction of a compound of the formula 
with a compound of the formula H2NR6 or H2NR7, wherein R6 and R7 are as described above. These reactions are often catalyzed by carboxylic acids, such as formic acid. Reactions such as these are described in Examples 1-3.
The iron complexes may be formed by reacting the appropriate tridentate ligand with an iron salt such as an iron halide or a compound such as iron [III] nitrate. See Examples 4-6 for preparation of iron complexes.
In the first oligomerization process (to produce xcex1-olefins) described herein an iron complex (I) is contacted with ethylene and a neutral Lewis acid W capable of abstracting Xxe2x88x92, hydride or alkyl (R20) from (I) to form a weakly coordinating anion, and must alkylate or be capable of adding a hydride ion to the iron atom, or an additional alkylating agent or an agent capable of adding a hydride anion to the iron atom must be present. The neutral Lewis acid is originally uncharged (i.e., not ionic). Suitable neutral Lewis acids include SbF5, Ar3B (wherein Ar is aryl), and BF3. Suitable cationic Lewis acids or Bronsted acids include NaBAF, silver trifluoromethanesulfonate, HBF4, or [C6H5NH(CH3)2]+[B(C6F5)4]xe2x88x92. In those instances in which (I) (and similar catalysts which require the presence of a neutral Lewis acid or a cationic Lewis or Bronsted acid), does not contain an alkyl or hydride group already bonded to the iron atom, the neutral Lewis acid or a cationic Lewis or Bronsted acid also alkylates or adds a hydride to the iron or a separate alkylating or hydriding agent is present, i.e., causes an alkyl group (R20) or hydride to become bonded to the iron atom.
It is preferred that R20 contains 1 to 4 carbon atoms, and more preferred that R20 is methyl or ethyl.
For instance, alkyl aluminum compounds (see next paragraph) may alkylate (I). However, not all alkylaluminum compounds may be strong enough Lewis acids to abstract Xxe2x88x92 or an alkyl group from the iron atom. In that case a separate Lewis acid strong enough to do the abstraction must be present. For instance, (C6F5)3B or (C6H5)3B are useful Lewis acids, and could be used in combination with, for example, an alkylaluminum compound such as triethylaluminum.
A preferred neutral Lewis acid, which can alkylate the iron, is a selected alkyl aluminum compound, such as R193Al, R19AlCl2, R192AlCl, and xe2x80x9cR19AlOxe2x80x9d (alkylaluminoxanes), wherein R19 is alkyl containing 1 to 25 carbon atoms, preferably 1 to 4 carbon atoms. Suitable alkyl aluminum compounds include methylaluminoxanes (which are oligomers with the general formula [MeAlO]n), (C2H5)2AlCl, C2H5AlCl2, and [(CH3)2CHCH2]3Al.
Metal hydrides such as NaBH4 may be used to bond hydride groups to the Fe.
In the second oligomerization process described herein an iron complex of (II) is either added to the oligomerization process or formed in situ in the process. In fact, more than one such complex may be formed during the course of the process, for instance formation of an initial complex and then reaction of that complex to form an active ended oligomer containing such a complex.
Examples of such complexes which may be formed initially in situ include 
wherein the xe2x80x9cRxe2x80x9d substituents are as defined above, T1 is hydride or alkyl or any other anionic ligand into which ethylene can insert, Y is a vacant coordination site, or a neutral ligand capable of being displaced by ethylene, and Q is a relatively non-coordinating anion. Complexes may be added directly to the process or formed in situ. For instance, (IV) may be formed by the reaction of (I) with a neutral Lewis acid such as an alkyl aluminum compound. Another method of forming such a complex in situ is combining a suitable iron compound such iron chloride, (II) and an alkyl aluminum compound. Other iron salts in which anions similar to chloride are present, and which may be removed by reaction with the Lewis or Bronsted acid. For instance iron halides, nitrates and carboxylates (such as acetates) may be used, particularly if they are slightly soluble in the process medium. It is preferred that these precursor iron salts be at least somewhat soluble in the process medium.
After the ethylene oligomerization has started, the complex may be in a form such as 
wherein, as before, the xe2x80x9cRxe2x80x9d substituents and Q are as defined above, and P is a divalent (oligo)ethylene group of the formula xe2x80x94(CH2CH2)xxe2x80x94 wherein x is an integer of 1 or more. The xe2x80x9cend groupxe2x80x9d on P in this instance is written as H, since as the oligomerization proceeds to form xcex1-olefins, the end group must of necessity be H. It could at some time, especially at the beginning of the oligomerization, be T1. It is preferred that Fe be in +2 oxidation state in (I), (IV), (V) and (VI).
Compounds such as (IV), (V) and (VI) may or may not be stable away from an environment similar to that of the oligomerization process.
(IV), (V) and (VI) may also be used, in the absence of any xe2x80x9cco-catalystsxe2x80x9d or xe2x80x9cactivatorsxe2x80x9d to oligomerize ethylene in a third oligomerization process. Except for the ingredients in the process, the process conditions for the third process, such as temperature, pressure, oligomerization medium, etc., may be the same as for the first and second oligomerization processes, and preferred conditions for those processes are also preferred for the third oligomerization process.
In all the oligomerization processes herein, the temperature at which it is carried out is about xe2x88x92100xc2x0 C. to about +300xc2x0 C., preferably about 0xc2x0 C. to about 200xc2x0 C., more preferably about 50xc2x0 C. to about 150xc2x0 C. It is preferred to carry out the oligomerization under ethylene (gauge) pressures from about 0 kPa to about 35 MPa, more preferably about 500 kPa to about 15 MPa. It is preferred that the oligomerization be carried under conditions at which the reaction is not significantly diffusion limited.
The oligomerization processes herein may be run in the presence of various liquids, particularly aprotic organic liquids. The catalyst system, ethylene, and xcex1-olefin product may be soluble or insoluble in these liquids, but obviously these liquids should not prevent the oligomerization from occurring. Suitable liquids include alkanes, alkenes cycloalkanes, selected halogenated hydrocarbons, and aromatic hydrocarbons. Specific useful solvents include hexane, toluene, the xcex1-olefins themselves, and benzene.
The formation of the xcex1-olefins as described herein is relatively rapid in many instances, and significant yields can be obtained in less than an hour. Under the correct conditions very high selectivity for an xcex1-olefin is shown, see for instance Examples 8-17.
Also under the correct conditions mixtures of xcex1-olefins containing desirable numbers of carbon atoms are obtained. A measure of the molecular weights of the olefins obtained is factor K from the Schulz-Flory theory (see for instance B. Elvers, et al., Ed. Ullmann""s Encyclopedia of Industrial Chemistry, Vol. A13, VCH Verlagsgesellschaft mbH, Weinheim, 1989, p. 243-247 and 275-276. This is defined as:
K=n(Cn+2 olefin)/n(Cn olefin)
wherein n(Cn olefin) is the number of moles of olefin containing n carbon atoms, and n(Cn+2 olefin) is the number of moles of olefin containing n+2 carbon atoms, or in other words the next higher oligomer of Cn olefin. From this can be determined the weight (mass) fractions of the various olefins in the resulting oligomeric reaction product mixture. The K factor is preferred to be in the range of about 0.7 to about 0.8 to make the xcex1-olefins of the most commercial interest. It is also important to be able to vary this factor, so as to produce those olefins which are in demand at the moment. Examples 8 to 17 show that this can be done in the present oligomerization processes.
The xcex1-olefins made herein may be further polymerized with other olefins to form polyolefins, especially linear low density polyethylenes, which are copolymers containing ethylene. They may also be homopolymerized. These polymers may be made by a number of known methods, such as Ziegler-Natta-type polymerization, metallocene catalyzed polymerization, and other methods, see for instance World Patent Application 96/23010, see for instance Angew. Chem., Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), European Patent Application 416,815 and U.S. Pat. No. 5,198,401 for information about metallocene-type catalysts, and J. Boor Jr., Ziegler-Natta Catalysts and Polymerizations, Academic Press, New York, 1979 and G. Allen, et al., Ed., Comprehensive Polymer Science, Vol. 4, Pergamon Press, Oxford, 1989, p. 1-108, 409-412 and 533-584, for information about Ziegler-Natta-type catalysts, and H. Mark, et al., Ed., Encyclopedia of Polymer Science and Engineering, Vol. 6, John Wiley and Sons, New York, 1992, p. 383-522, for information about polyethylenes, and all of these are hereby included by reference.
The xcex1-olefins made herein may be converted to alcohols by known processes, these alcohols being useful for a variety of applications such as intermediates for detergents or plasticizers. The xcex1-olefins may be converted to alcohols by a variety of processes, such as the oxo process followed by hydrogenation, or by a modified single step oxo process (the xe2x80x98modified Shell processxe2x80x99), see for instance B. Elvers, et al., Ed., Ullmann""s Encyclopedia of Chemical Technology, 5th Ed., Vol. A18, VCH Verlagsgesellschaft mbH, Weinheim, 1991, p. 321-327, which is hereby included by reference.
The ethylene oligomerizations herein may also initially be carried out in the solid state by, for instance, supporting and active catalyst or catalyst precursor on a substrate such as silica or alumina. If a catalyst precursor, such as an iron halide or nitrate, it may be activated with a Lewis (such as W, for instance an alkylaluminum compound) and exposing it to ethylene. Alternatively a solution of the catalyst precursor may be exposed to a support having an alkylaluminum compound on its surface. The support may also be able to take the place of the Lewis or Bronsted acid, for instance an acidic clay such as montmorillonite. Another method of making a supported catalyst is to start a polymerization or at least make an iron complex of another olefin or oligomer of an olefin such as cyclopentene on a support such as silica or alumina. All of these xe2x80x9cheterogeneousxe2x80x9d catalysts may be used to catalyze oligomerization in the gas phase or the liquid phase. By gas phase is meant that the ethylene is transported to contact with the catalyst particle while the ethylene is in the gas phase.
Some of the compounds made or used in the Examples are shown below: 